利用curl下载文件(进度条显示)

利用curl下载文件(进度条显示) 在项目中需要用到程序更新的功能,同事介绍说是curl中的开发库很不错,于是下载这个包测试了一下，确实不错。准备正式用到项目中，以下一个例子用于从互联网上抓取一个文件下载到本地，并加上进度条显示，做得挺简陋，不过功能差不多就这样了。 程序运行预览. 首先需要加入多线程的机制，因为程序一边在下载文件，一边在显示进度条，单线程的方式肯定不行，所以我用到了wxTimer来实现,在downloadMain.h 中定义了一个wxTimer，并做了事件申明. DECLARE_EVENT_TABLE() /*************************************************************** * Name: downloadMain.h * Purpose: Defines Application Frame * Author: () * Created: 2008-11-14 * Copyright: () * License: **************************************************************/ #ifndef DOWNLOADMAIN_H #define DOWNLOADMAIN_H #include "downloadApp.h" #include #include "GUIDialog.h" class downloadDialog: public GUIDialog { public: downloadDialog(wxDialog *dlg); ~downloadDialog(); void .Timer(wxTimerEvent& event); private: virtual void .Close(wxCloseEvent& event); virtual void .Quit(wxCommandEvent& event); virtual void .About(wxCommandEvent& event); void downloadfile(); wxTimer* m_timerdown; DECLARE_EVENT_TABLE() }; #endif // DOWNLOADMAIN_H 下面是主程序的代码. /*************************************************************** * Name: downloadMain.cpp * Purpose: Code for Application Frame * Author: (alan) * Created: 2008-11-14 * License: **************************************************************/ #ifdef WX_PRECOMP #include "wx_pch.h" #endif #ifdef __BORLANDC__ #pragma hdrstop #endif //__BORLANDC__ #include "downloadMain.h" #include #include #include #include "update.h" #include #include #define TIMER_ID 22222 //事件监听声明 BEGIN_EVENT_TABLE(downloadDialog, GUIDialog) EVT_TIMER(TIMER_ID, downloadDialog::OnTimer) END_EVENT_TABLE() enum wxbuildinfoformat { short_f, long_f }; wxString wxbuildinfo(wxbuildinfoformat format) { wxString wxbuild(wxVERSION_STRING); if (format == long_f ) { #if defined(__WXMSW__) wxbuild << _T("-Windows"); #elif defined(__WXMAC__) wxbuild << _T("-Mac"); #elif defined(__UNIX__) wxbuild << _T("-Linux"); #endif #if wxUSE_UNICODE wxbuild << _T("-Unicode build"); #else wxbuild << _T("-ANSI build"); #endif // wxUSE_UNICODE } return wxbuild; } //声明一个文件结构体 struct FtpFile { char *filename; FILE *stream; }; downloadDialog::downloadDialog(wxDialog *dlg) : GUIDialog(dlg) { //创建一个定时器,制定TIMER_ID m_timerdown = new wxTimer(this, TIMER_ID); //定时器开始运行,这里会自动执行OnTimer函数 m_timerdown->Start(100); } downloadDialog::~downloadDialog() { } //定时器操作 void downloadDialog::OnTimer(wxTimerEvent &event) { downloadfile(); } //文件写入流 int my_fwrite(void *buffer, size_t size, size_t nmemb, void *stream) { struct FtpFile *out=(struct FtpFile *)stream; if (out && !out->stream) { out->stream=fopen(out->filename, "wb"); if (!out->stream) { return -1; } } return fwrite(buffer, size, nmemb, out->stream); } //进度条显示函数 int wxcurldav_dl_progress_func(void* ptr, double rDlTotal, double rDlNow, double rUlTotal, double rUlNow) { wxGauge* pGauge = (wxGauge*) ptr; if(pGauge) //设置进度条的值 pGauge->SetValue(100.0 * (rDlNow/rDlTotal)); return 0; } //下载文件函数 void downloadDialog::downloadfile() { //创建curl对象 CURL *curl; CURLcode res; m_staticText2->SetLabel(wxT("请耐心等待程序下载更新包...")); struct FtpFile ftpfile= { //定义下载到本地的文件位置和路径 "tmp.exe",NULL }; curl_global_init(CURL_GLOBAL_DEFAULT); //curl初始化 curl = curl_easy_init(); //curl对象存在的情况下执行操作 if (curl) { //设置远端地址 curl_easy_setopt(curl, CURLOPT_URL," setup.EXE"); //执行写入文件流操作 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_fwrite); curl_easy_setopt(curl, CURLOPT_WRITEDATA, &ftpfile); //curl的进度条声明 curl_easy_setopt(curl, CURLOPT_NOPROGRESS, FALSE); //回调进度条函数 curl_easy_setopt(curl, CURLOPT_PROGRESSFUNCTION, wxcurldav_dl_progress_func); //设置进度条名称 curl_easy_setopt(curl, CURLOPT_PROGRESSDATA, m_gauge1); //进度条 m_gauge1->SetValue(0); //写入文件 res = curl_easy_perform(curl); m_gauge1->SetValue(100); //释放curl对象 curl_easy_cleanup(curl); if (CURLE_OK != res) ; } if (ftpfile.stream) { //关闭文件流 fclose(ftpfile.stream); } //释放全局curl对象 curl_global_cleanup(); //这一步很重要，停止定时器,不然程序会无休止的运行下去 m_timerdown->Stop(); //执行刚下载完毕的程序,进行程序更新 int pid = ::wxExecute(_T("tmp.exe")); wxMessageBox(wxT("下载完毕，程序开始执行更新操作......")); } void downloadDialog::OnClose(wxCloseEvent &event) { Destroy(); } void downloadDialog::OnQuit(wxCommandEvent &event) { Destroy(); } void downloadDialog::OnAbout(wxCommandEvent &event) { }